Justification:Antirrhinum lopesianum is listed as Endangered for it presents a severely fragmented distribution, with a low area of occupancy, below 500 km². Regressive trends have been observed in the quality of its habitat. A probability of extinction of 33% in 20 years has been calculated for the species in its biggest subpopulation and prospects for the other subpopulations are probably worse.

This plant is endemic to the Iberian Peninsula, occurring at the northeastern border of Portugal with Spain. Its main population is located in Portugal. In Spain, the species is known from four subpopulations (Iriondo et al. 2009). According to Bernardos et al. (2006) there are four subpopulations in Portugal, in the rivers Sabor-Maças and five-six more subpopulations can be found in the border of Portugal and Spain, along Duero river. Total number of subpopulations is, therefore, around ten. Areas of occupancy of around 0.029 km² in Portugal and 2 km² in Spain, have been reported.

In Spain, total population size has been reported to be 248 individuals, from which 242 specimens occur in the location Corporario (Salamanca), which appears fragmented. Extreme annual fluctuations have been observed in the number of mature individuals due to drought events (González Talaván et al. 2004). Four subpopulations occur in Portugal, in the rivers Sabor-Maças and five-six more subpopulations can be found in the border of Portugal and Spain, along the Duero river. The total number of subpopulations is therefore around ten. Total number of individuals thought to exist is only 768 (Bernardos et al. 2006), distributed along the valley of the River Duero on the Spanish-Portuguese border (562, 71.2%), and in the Portuguese Sabor River valley (206, 26.8%).

This perennial chamaephyte grows on calcareous rocks on the banks of the River Duero (northeast Portugal and central western Spain) and River Sabor (northeast Portugal). It has a linear spatial distribution of individuals along the banks of rivers. Flowering occurs in spring (April-May), and fructification in summer (July-September); it is insect pollinated.

In Portugal, this herb grows in fissures in more or less overhanging granitic walls with carbonate crusts, facing north or east, in association with Rumici-Dianthion lusitani communities. In Spain, it occurs on steep granitic walls with carbonate crusts, within casmophytic communities. Frequent accompanying species are Phagnalon saxatile, Rumex induratus and Dianthus lusitanus. In Salamanca, the Iberian endemism Scrophularia valdesii can also be found growing along with Antirrhinum lopesianum.

The main threat to the species is loss of habitat: about one third of the Iberian populations can be considered threatened (Bernardos et al. 2006). In Portugal, main threats affecting the species are collection, leisure and tourism impacts, trampling caused by the use of paths and cycling tracks, forest planting activities, water pollution and drying out (Commission of the European Communities 2009). In Spain, main threats to the species is its poor reproductive strategy (González Talaván et al. 2004). Furthermore, the location in Salamanca is close to a recreational area and it is easily accessible.

Antirrhinum lopesianum is listed on Annex IV of the Habitats Directive.

It is included as species with “Protección Especial” in the national list of species in regime of special protection of Spain and as species "En peligro de extinción" in the regional catalogue of threatened species of Castilla y León. It is listed as Endangered (EN) B2ab(v); C2a(i); D in the Spanish Red List (Moreno 2008). It occurs within the protected area Parque Natural de Arribes del Duero. The location in Salamanca is expected to be included in an SCI.

In Portugal, the species presents poor prospects and it is likely to struggle unless conditions change. It is classifiable as Critically Endangered in this country (Bernardos et al. 2006), based on IUCN criteria, i.e., area of occupancy less than 10 km², severely fragmented, number of mature individuals declining, and only 284 mature individuals in total: CR B2ab(v) (Bernardos et al. 2006).

Seeds should be collected and stored in germplasm banks, education and awareness programmes for visitors should be developed. Population trend monitoring should be kept in place.